The present invention relates to laboratory pipets for changing liquid residing in a vessel, e.g., a tissue culture vessel. Changing liquid medium is routine (often called cell feeding) in laboratories that use cell/tissue cultures and is generally performed every other day. The conventional operation of cell feeding typically involves at least two separate steps: 1) removal or aspiration of the old medium from a culture vessel by means of vacuum suction or pipetting; and 2) addition of new medium to the culture vessel using another pipet to transfer medium from a liquid container to the culture vessel.
Conventional laboratory pipets, which are usually used with an electrical/mechanical pipetter for drawing and expelling fluids, have a single barrel and therefore can handle (take and discharge) only one liquid at a time. This process requires a change of pipets, thereby rendering the process discontinuous and requiring many actions, pauses, openings of culture vessels and medium containers, and seconds or minutes of prolonged exposure of cultured cells to air. Consequently, cell feeding is time consuming, material-wasting, and potentially harmful to cultured cells, particularly when a large volume of medium or a large number of vessels are involved.
To solve the aforementioned problems, a method and apparatus for a one-step liquid medium exchange is described in U.S. Pat. No. 5,874,296, which is hereby incorporated by reference. The apparatus comprises a vacuum controller, a pipe, and a reservoir. The apparatus is capable of suctioning a liquid (old medium) from a container using a vacuum and simultaneously drawing a second liquid (new medium) from a liquid source to fill the reservoir. When the old medium is completely extracted and sufficient new medium fills the reservoir, the vacuum controller disengages the vacuum to stop fluid transfer. Activation of another controller allows the new medium to drain from the reservoir into the now empty container which formerly contained the old medium. Use of this apparatus can now accomplish the task of changing liquid media in essentially one step. An installed vacuum source is generally required for operation of the apparatus.
The present invention is based on a variety of new features that increase the flexibility and efficiency of the one-step liquid medium exchange system described in U.S. Pat. No. 5,874,296. In one embodiment, a pipet includes a first reservoir for holding the liquid to be freshly added to a vessel, and a second reservoir for holding the waste liquid removed from the vessel. Visual inspection of the fluid levels in the first and second reservoirs helps the user confirm both the volume of liquid removed from the vessel and the volume of liquid to be introduced into the vessel. In another embodiment, a pipet controller includes a conduit and valve control system for controlling liquid flow through the controller, in contrast to previously available pipet controllers that do not allow liquid to flow through the controller.
Accordingly, the invention features a pipet having (1) a delivery reservoir including an inlet port that allows passage of liquid into but not out of the delivery reservoir, the inlet port adapted for attachment to a liquid source, and an outlet-port that allows passage of liquid out of but not into the delivery reservoir, the delivery reservoir formed of a material substantially transparent to allow visual inspection of liquid level within the delivery reservoir; (2) a disposal reservoir including an inlet port that allows passage of liquid into but not out of the disposal reservoir, and an outlet port that allows passage of liquid out of but not into the disposal reservoir, the outlet port adapted for attachment to a waste receptacle, and the disposal reservoir formed of a material substantially transparent to allow visual inspection of liquid level within the disposal reservoir, (3) a tube having a distal end and proximal end, the distal end adapted for suction of liquid from and delivery of liquid to a vessel, and the proximal end in communication with the outlet port of the delivery reservoir and the inlet port of the disposal reservoir, and (4) a vacuum port contiguous with the delivery reservoir and the disposal reservoir and adapted for attachment to a vacuum source.
In an alternative embodiment, the invention includes a pipet having (1) a delivery reservoir including an inlet port that allows passage of liquid into but not out of the delivery reservoir, the inlet port adapted for attachment to a liquid source, and an outlet port that allows passage of liquid out of but not into the delivery reservoir, the delivery reservoir formed of a material substantially transparent to allow visual inspection of liquid level within the delivery reservoir, (2) a disposal reservoir including
an inlet port that allows passage of liquid into but not out of the disposal reservoir, and
an outlet port that allows passage of liquid out of but not into the disposal reservoir, the outlet port adapted for attachment to a waste receptacle, and the disposal reservoir formed of a material substantially transparent to allow visual inspection of liquid level within the disposal reservoir; (3) a suction tube having a distal end adapted for suction of liquid from a vessel and a proximal end in communication with the inlet port of the disposal reservoir; (4) a delivery tube having a distal end adapted for delivery of liquid from a vessel and a proximal end in communication with the outlet port of the delivery reservoir; and (5) a vacuum port contiguous with the delivery reservoir and the disposal reservoir and adapted for attachment to a vacuum source,
Application of a vacuum to the pipets via the vacuum port causes passage of liquid from the liquid source into the delivery reservoir via its inlet port and simultaneous passage of liquid from the vessel through the tube and into the disposal reservoir via its inlet port. In addition and optionally, release of the vacuum subsequent to the application of the vacuum causes passage of liquid from the delivery reservoir via its outlet port through the tube and into the vessel and simultaneous passage of liquid from the disposal reservoir via its outlet port to the waste receptacle.
The pipets of the invention can include one or more of the following optional features: The delivery and disposal reservoir are arranged side by side. The inlet port and outlet port of the delivery reservoir each includes a clack valve. The inlet port and the outlet port of the disposal reservoir each includes a clack valve. The tube is substantially rigid. The vacuum port includes a filter that blocks the passage of liquid and/or air particles into and out of the pipets. The distal end of the tube is adapted for simultaneous suction of liquid from and simultaneous delivery of liquid to a plurality of vessels (e.g., a two-dimensional array of vessels). The distal end of the tube includes a filter that blocks passage of cells while allowing liquid to flow through the tube.
The invention further includes a pipet controller having (1) a housing including an inlet port and an outlet port, the inlet port adapted to engage a pipet and the outlet port adapted for attachment to a vacuum source; (2) a conduit within the housing and connected to the inlet port and the outlet port; and (3) an adjustable valve system for controlling liquid flow through the conduit, the valve system having at least a first setting in which the vacuum source applies a vacuum to the pipet through the conduit, thereby allowing suctioning of liquid from the pipet through the conduit, and a second setting in which the vacuum source is disconnected from the conduit, thereby releasing liquid in the pipet.
The controller can have one or more of the following optional features: The valve system further has a third setting in which the vacuum source is disconnected but a homeostatic suction is maintained on the pipet the valve system includes at least one spring-loaded piston. The controller is formed of only autoclavable materials.
Also featured in the invention is a container lid having a housing defining at least a first and second passage, the first passage configured to seal a container opening having a first configuration, and the second passage configured to seal a container opening having a second configuration different from the first configuration.
The lids of the invention can have one or more of the following optional features: The first and second configurations are cylindrical but are of different diameters. The first and second passages are threaded and configured to seal a screw-top bottle. The lids further include an outlet port adapted for dispensing of liquid from the container. The outlet port is sealable. The lids further include a suction tube extending from the outlet port and into a container.
The invention also includes a pipet having (1) a delivery reservoir including an inlet port adapted for connection to a liquid source, and an outlet port including a valve that allows passage of liquid out of but not into the delivery reservoir; (2) a tube having a distal end and proximal end, the distal end adapted for suction of liquid from and delivery of liquid to a vessel, and the proximal end in communication with the outlet port of the delivery reservoir; and (4) a vacuum port contiguous with the delivery reservoir and adapted for attachment to a disposal receptacle and a vacuum source. Application of a vacuum to the pipet via the vacuum port causes passage of liquid from the liquid source into the delivery reservoir via its inlet port and simultaneous passage of liquid from the vessel through the tube, out of the vacuum port, and into the disposal receptacle.
The present pipet can be used with a mechanical pipetter widely used in laboratories, any installed vacuum source, or a pipet controller described herein. This pipet has a simple construction that can be operated easily and accurately and is versatile. Other features and advantages will be apparent from the following detailed description.